A bond is not simply an investment that “pays interest.” It is a debt claim built from a set of promises. Someone borrows. Someone lends. A principal amount is defined. Payment dates are specified. A maturity date says when the claim is due to end. Other terms determine what happens before, during and after that journey.
The price at which a bond later trades can move every day. The underlying contractual structure does not automatically move with it. A bond with S$1,000 face value and a 4% fixed coupon may trade above S$1,000, below S$1,000 or close to S$1,000 while still promising the same contractual coupon and principal—unless the issuer defaults, restructures the debt, exercises a contractual option or another term changes the outcome.
This article begins at the claim rather than the price screen. It belongs to the bond route inside How Finance Works. The later companion article on bond prices and yields will explain why the market value changes; this page owns the debt contract itself.
Educational scope: general bond mechanics. Actual rights depend on the prospectus, trust deed or indenture, governing law, issuer and security structure. Examples are simplified and are not investment, legal or tax advice.
A bond is a debt security
Investor.gov describes a bond as a debt security: the issuer borrows money from investors for a period of time and promises specified payments. In the simplest fixed-rate form, the issuer pays periodic interest and returns the principal when the bond matures. See Investor.gov’s bond overview.
That definition immediately separates a bond from a share. A shareholder owns an equity claim. A bondholder is a creditor under the bond’s terms. The shareholder may participate in unlimited upside if the company becomes more valuable; the bondholder normally receives the contractual debt payments rather than an unlimited share of the company’s success.
The difference matters because the same company can have many claim layers at once: bank loans, secured bonds, unsecured bonds, trade creditors, preference shares and ordinary shares. “I invested in Company X” is therefore incomplete. The instrument determines the position.
Five parts of the basic bond promise
| Part | Question it answers |
|---|---|
| Issuer | Who owes the money? |
| Principal / face value | What amount is the debt claim based on? |
| Coupon | How is periodic interest calculated and paid? |
| Maturity | When is the principal contractually due? |
| Terms and priority | What other rights, protections, options and ranking rules apply? |
These five parts are the minimum map. Real bonds can add call provisions, put rights, conversion features, covenants, collateral, floating-rate formulas, step-up coupons, sinking funds, guarantees and many other terms.
Principal, face value and par value
The face value, also called par value or principal amount in many simple explanations, is the reference amount used in the bond contract. A bond with S$1,000 face value and a 5% annual fixed coupon pays S$50 of coupon per year under the simplified assumption that the rate applies directly to that face amount.
The market price can be different. If that bond trades for S$950, the contractual face value has not become S$950. The investor has paid S$950 for a claim whose contractual principal remains S$1,000 under the example. If it trades for S$1,050, the principal promise still does not become S$1,050.
This is one of the most important distinctions in bond finance: contractual amount and market value are different quantities.
Coupon rate and coupon payment
Investor.gov explains that many corporate bonds pay a fixed coupon, while others use floating rates and some pay no periodic coupon at all. The coupon rate tells you how the contractual interest payment is determined; it does not tell you the market return available to a new buyer at today’s price. See Investor.gov’s corporate-bond bulletin.
Suppose a S$1,000 bond has a 4% annual coupon and pays twice a year. The annual coupon is S$40. Under the simplified semi-annual schedule, each payment is S$20. If the market price later changes to S$900 or S$1,100, the fixed S$40 annual contractual coupon remains S$40 unless the bond terms say otherwise.
That is why coupon and yield must not be treated as synonyms. Coupon belongs to the bond contract. Yield is a market return measure built from the bond’s price and cash flows.
Fixed-rate, floating-rate and zero-coupon bonds
A fixed-rate bond keeps its contractual coupon rate unchanged for the relevant period. A floating-rate bond resets using a benchmark or formula specified in the terms. A zero-coupon bond does not make ordinary periodic coupon payments; instead, its return is built into the difference between the purchase price and the amount paid at maturity, subject to the instrument’s terms.
These structures place interest-rate risk differently. A fixed coupon leaves the cash payment unchanged while market rates move around it. A floating coupon partially resets with the benchmark, which can reduce one form of rate exposure while creating uncertainty about future income. A zero-coupon structure concentrates the contractual payment at maturity and generally becomes more sensitive to discount-rate changes because more of its value sits further in the future.
The label “bond” therefore describes a family of debt claims, not one universal cash-flow pattern.
Maturity: when the debt is contractually due
Maturity is the date when the principal is due under the bond’s contractual structure, assuming the instrument has not been called, converted, restructured or otherwise altered before then. A three-year bond and a thirty-year bond can have the same issuer and coupon rate while carrying very different time exposure.
Time changes several risks. The longer the claim extends, the more opportunities there are for interest rates, inflation, the issuer’s credit quality, regulation, business conditions and market liquidity to change. Longer maturity also changes how heavily distant cash flows are affected by the discount rate.
This is why the earlier Time Inside Finance article matters: every bond promise lives on a calendar.
A worked bond from issue to maturity
Take a fictional five-year bond with S$1,000 face value, a 4% fixed annual coupon and annual payments. Ignore tax, fees, default and reinvestment.
| Year | Coupon | Principal | Total contractual cash flow |
|---|---|---|---|
| 1 | S$40 | — | S$40 |
| 2 | S$40 | — | S$40 |
| 3 | S$40 | — | S$40 |
| 4 | S$40 | — | S$40 |
| 5 | S$40 | S$1,000 | S$1,040 |
These are promised cash flows, not guaranteed economic outcomes. If the issuer cannot pay, the contract becomes a claim in distress rather than a machine that manufactures cash regardless of reality.
Issue price and secondary-market price answer different questions
In the primary market, the bond is first sold to investors and the issuer receives financing, net of the relevant issuance structure and costs. In the secondary market, an existing investor can sell the bond to another investor. The issuer normally does not receive fresh funding from that resale.
This distinction is the bond version of the broader mechanism explained in Primary vs Secondary Markets. The bond can change hands many times while the issuer’s contractual debt remains the same claim.
A market price is therefore the current price of the claim, not the amount originally raised and not the principal automatically due at maturity.
The issuer matters because the promise needs a payer
Bonds can be issued by governments, corporations and other entities. The legal form is similar enough that they sit in the same broad debt-security family, but the economic support behind the promise can differ dramatically.
A corporate bond depends on the company and the claim’s position in the company’s capital structure. A sovereign bond depends on the issuing government’s fiscal, monetary, legal and institutional capacity, and the result can differ depending on whether the debt is issued in the government’s own currency or another currency. A public-sector issuer, state-linked company and national government should not be collapsed into one generic label.
The later article Government Bonds vs Corporate Bonds owns this issuer-risk comparison. The key point here is that a bond contract only becomes useful when the issuer can honour it.
Collateral and security: which assets stand behind the claim?
Some bonds are secured by specified collateral or security interests. Others are unsecured obligations supported by the issuer’s general credit. Security can improve the creditor’s position, but it does not make loss impossible. Collateral can fall in value, be disputed, rank behind another claim or take time and cost to realise.
The correct question is not “Is this bond secured?” followed by automatic comfort. It is: secured by what, with which priority, under which law, and what could that collateral actually realise under stress?
For the underlying mechanism, see Collateral | Why Another Asset Can Stand Behind a Promise.
Covenants: boundaries written into the debt
A bond can include covenants that restrict behaviour or require specified actions. These can help creditors monitor risk before the payment actually fails. The exact covenant package depends on the instrument and market.
A covenant is not a guarantee that the company will remain safe. It is a rule inside the relationship. If the issuer approaches or breaches a covenant, the event can trigger negotiation, waiver, repricing, additional security, repayment or other consequences under the terms.
Read the deeper mechanism in Covenants | How Lenders Put Boundaries Around Borrower Behaviour.
Call provisions: the issuer may be able to repay early
Some bonds give the issuer the contractual right to redeem the bond before final maturity under specified conditions. This is a call feature. If market rates fall, an issuer may have an incentive to refinance expensive debt, subject to the bond terms and economic costs.
That creates reinvestment risk for the bondholder. A high-coupon bond may be most likely to be called when its coupon is most attractive relative to the current market. The holder receives the contractual call price rather than an unlimited right to keep collecting the old coupon until the original maturity date.
This is why yield-to-call and yield-to-worst can matter in analysis. The instrument’s earliest economically plausible exit path may differ from the final legal maturity.
Put provisions and investor optionality
A puttable bond can give the investor a contractual right to require repayment at specified times or under specified conditions. This shifts part of the timing option from issuer to holder.
Optionality has value because it changes what each side can do when rates, credit conditions or circumstances move. The analytical habit is to ask: who owns the option, when can it be exercised, and how does that alter the cash-flow path?
A bond with the same coupon and maturity as another bond can therefore still be economically different because one side owns a valuable option that the other structure does not contain.
Convertible bonds: debt that may become equity
Some bonds can convert into shares according to specified terms. Before conversion they are debt claims. After conversion, the holder’s position becomes equity under the conversion structure. This hybrid feature links bond analysis to dilution and shareholder ownership.
Suppose a S$1,000 convertible can exchange into 50 shares. The implied conversion price is S$20 a share. If the equity becomes very valuable, conversion may become attractive. But the actual decision can depend on call features, maturity, credit risk, accrued payments and other contractual terms.
The bond should not be analysed as pure debt while ignoring the conversion option, and the potential shares should not be treated as though conversion has already happened. The claim has conditional states.
A bond can be safe from one risk and exposed to another
“Fixed income” is sometimes mistaken for “fixed value.” The income schedule may be fixed while the market price remains variable. The issuer may be strong while inflation erodes purchasing power. The bond may be liquid in normal markets and hard to sell during stress. The principal may be contractually due in full while the issuer’s ability to pay becomes uncertain.
| Risk | What can change? |
|---|---|
| Interest-rate risk | Market discount rates change, moving the price of fixed cash flows. |
| Credit risk | The issuer’s ability or willingness to pay deteriorates. |
| Inflation risk | Nominal payments buy less in real terms. |
| Liquidity risk | Trading becomes costly or difficult before maturity. |
| Reinvestment risk | Coupons or called principal must be reinvested at lower rates. |
| Currency risk | The bond’s currency moves against the holder’s spending currency. |
| Legal / structural risk | Priority, collateral, guarantees or terms behave differently than assumed. |
One instrument can carry several of these simultaneously. Risk analysis is not a single score.
Clean price, accrued interest and the cash paid on settlement
Bond markets often quote a clean price that excludes accrued interest. Between coupon dates, the buyer may pay the seller compensation for the coupon interest that has economically accrued during the seller’s holding period. The amount actually paid can therefore differ from the quoted clean price.
Singapore’s MAS SGS data explicitly notes that bond prices are quoted per S$100 of principal on a clean basis, excluding applicable accrued interest. See the MAS SGS bond price and yield tables.
This is a useful operational reminder: market quotation, contractual principal and settlement cash are three different quantities.
The promise is only as good as the full payment route
For a bond payment to reach a holder, the issuer must have the ability and willingness to pay; the paying and settlement infrastructure must function; the security must be correctly recorded; and intermediaries or custodians must pass the money through the chain.
Most of the time these layers are invisible because they work. During default, sanctions, market disruption or operational failure, the distinction between a valid contractual right and a successfully received payment becomes visible.
This is the finance version of a wider systems lesson: a promise is not complete until the receiver can actually use the result.
The reverse test: read the bond from failure backwards
Instead of beginning with the coupon, begin with the failure case. If the issuer cannot pay the next coupon, what rights does the bondholder have? If the issuer liquidates, where does this bond rank? Is there collateral? A guarantee? A trustee? Cross-default terms? A cure period? Which jurisdiction governs the claim?
Then work backwards into normality. If those failure rights are acceptable, ask whether the coupon compensates for the risk, whether the maturity fits the holder’s time horizon, and whether the price makes the promised cash flows attractive relative to alternatives.
This method does not assume failure is likely. It prevents the good-state coupon from hiding the bad-state contract.
An observable mastery test
A five-year bond has S$1,000 face value, a 4% fixed coupon and trades at S$920. A reader says, “The company must now repay only S$920 because that is what the bond is worth.”
The correction is straightforward. S$920 is the current market price under the example. The contract still specifies the S$1,000 principal payment at maturity, assuming no default or other contractual event changes the outcome. The lower price reflects the market’s required return and risk assessment, not an automatic rewrite of principal.
You understand the bond when you can keep four numbers separate: principal, coupon, market price and yield. The next article will connect those four without collapsing them.
The World Return of a bond
Borrowing need → bond terms → investor funding → issuer uses capital → issuer generates fiscal or operating capacity → coupons and principal become payable → payments or losses reach bondholders.
The financial claim is useful because it coordinates present funding with future repayment. Its quality therefore depends on what happens between those two moments. A bond can finance productive infrastructure, a business expansion, refinancing, working capital or many other purposes. The contract tells us how the debt is structured; the real-world use of the money tells us whether the structure is building the capacity required to honour it.
That is the bond’s deepest test: does the future payer become capable of carrying the future claim?
Sources and further reading
Core definitions are supported by Investor.gov’s bond FAQ, its corporate-bond bulletin, and the Monetary Authority of Singapore’s SGS price and yield tables. The worked cases are original teaching examples.
Continue through the bond series
Continue to Why Bond Prices and Yields Move in Opposite Directions, then Government Bonds vs Corporate Bonds and Bond Default. Return to How Finance Works for the complete financial-system map.